Materials of a high permittivity or high-k value are of special interest for manufacturing semiconductor devices like capacitors. As an example, FIG. 1 illustrates a capacitor structure in a substrate 1, made of an outer electrode 2, a dielectric layer 3 and an inner electrode 4. Most modern capacitor structures use a similar arrangement. As capacity scales having a permittivity of the dielectric layer 3 respective materials are preferably chosen from materials having a high permittivity, so-called high-k dielectrics, As further a capacity inversely scales having the thickness of the dielectric layer 3 commonly these layers 3 are made thinner than 20 nm or even thinner than 10 nm.
The high-k dielectric layers are deposited in an amorphous state upon the substrate 1 or a first electrode 2. However, it appears that these materials tend to form a polycrystalline layer due to subsequent thermal steps. Such a polycrystalline layer is schematically illustrated in FIG. 2 having crystalline grains 10 and conductive channels 11 formed along the grain boundaries. These conductive channels 11 are considered to be a cause for leakage currents from the first electrode 2 to the second electrode 4. This is especially the case when the thickness of the dielectric layer 3 and the diameter of the grains 10 are of same order. Then, conductive channels 11 may be formed by just one or two grains connecting the electrodes 2, 4 having a relatively low resistance. The conductive channels 11 reduce the resistance of the dielectric layer. Especially, the resistance of layers having a width less than 20 nm is dominated by these conductive channels.